Detecting targets in roadway intersections

ABSTRACT

The present invention extends to detecting targets in roadway intersections. A traffic sensor includes a transducer system and a transceiver system. The transducer system creates a plurality of transducer views for detecting targets located in a portion of the intersection. The transducer system includes a transducer configured to transmit signals towards and to receive signals and signal reflections within a portion of the two or more approaches to the intersection. The transducer is configured such that when necessary the transducer can transmit a signal and receive a signal or signal reflection simultaneously. The transceiver system is configured to generate digital data indicative of the transducer receiving a signal or signal reflection. The transducer system and transceiver system interoperate to generate an aggregate sensor view of the intersection that includes a plurality of transducer views of the two or more approaches to the intersection.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. utility patent application Ser.No. 11/614,250 filed on Dec. 21, 2006, entitled DETECTING TARGETS INROADWAY INTERSECTIONS; which is a continuation of U.S. utility patentapplication Ser. No. 11/311,103 filed on Dec. 19, 2005 now abandoned,entitled DETECTING TARGETS IN ROADWAY INTERSECTIONS, which areincorporated herein in their entireties.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to detecting targets in roadwayintersections.

2. The Relevant Technology

The use of traffic sensors for the actuation of traffic signal lightslocated at the intersection of roadways is quite common. Generally, suchtraffic sensors can provide input used to properly actuate trafficcontrol devices in response to the detection or lack of detection ofvehicles. For example, traffic sensors can enable a traffic controldevice to skip unnecessary signal phases, such as, for example, skippinga left hand turn phase when no vehicles are detected in a correspondingleft hand turn lane. Traffic sensors can also enable a traffic signal toincrease green light duration for major arterials by only signaling thegreen light in the minor cross streets when vehicles are detected on theminor cross streets and thus minimizing the red light for a majorarterial. Thus, traffic sensors assist in properly actuating asignalized intersection to improve traffic flow. In addition to theactuation of signalized intersections of roadways for automobiletraffic, traffic sensors are also used for the actuation ofintersections of a roadway for automobile traffic with a railway.

Unfortunately, the cost of traffic sensors and cost of correspondinginstallation can be relatively high. Thus, traffic sensors and relatedcosts can become a significant expenditure for municipalities. The highinstallation costs arise at least in part from the need to installsensors for every approach to an intersection.

Typically, traffic signal lights have been actuated using inductive loopdetectors embedded in the roadway. Inductive loop detectors are veryexpensive to install since lane closures are necessary. The high cost iscompounded, especially for multi-lane roadways, since at least oneinductive loop detector is required for each detection zone (e.g., lefthand turn lane detection zones, through lane detection zones, and righthand turn lane detection zones). Furthermore, inductive loop detectortechnology is often unreliable and inductive loop detectors require agreat deal of calibration.

Video detectors are also used in some traffic signal actuation systems.To facilitate traffic signal light actuation, a video camera is placedhigh above a signal arm such that the video camera's view covers oneapproach to the intersection. The video signal from the camera isdigitally processed to create detections in the defined zones. Usingvideo detectors an intersection can be monitored on a per approach basis(that is all the lanes of an approach), as opposed to the per detectionzone basis used with inductive loops. However, at least one camera perapproach is required. Since a dedicated mounting arm is often necessaryand at least one camera per approach is required, the installation of avideo detector system can also be expensive and time consuming.

Microwave detectors have also been used in intersections to providedetection coverage over limited areas. At least one microwave detectorhas a limited degree of mechanical and electrical steering. However,similar to video detectors, one microwave detector per approach isrequired and the coverage is typically over a small portion of theintersection. Further, manual configuration is needed to ensure that theproper detection zones from each sensor are wired to the proper input inthe traffic controller.

Other microwave sensors have included multiple receive antennas but haveincluded only a single transmit antenna that has a very broad main beamor even may be an omni-directional antenna. Systems that employ only onebroad beam or omni-directional transmit antenna typically cannot achievean appropriately reduced side lobe power level. Furthermore, thesesingle transmit antenna systems typically suffer from widening of themainlobe.

Acoustic sensors have also been used in intersections to cover limiteddetection zones. However, these sensors also require one unit perapproach. Therefore intersection traffic detection products that reducethe number of sensors and sensor installations required would beadvantageous.

BRIEF SUMMARY OF THE INVENTION

The foregoing problems with the prior state of the art are overcome bythe principles of the present invention, which are directed towardsmethods, systems, and computer program products for detecting targets inroadway intersections. A traffic sensor includes a transducer system anda transceiver system.

The transducer system creates a plurality of transducer views of theroadway intersection. Each transducer view can detect targets located ina portion of the roadway intersection. The transducer system includes atransducer configured to transmit signals towards a portion of two ormore approaches to the roadway intersection and configured to receivesignals and signal reflections within the portions of the two or moreapproaches to the roadway intersection.

The transceiver system is configured to generate digital data indicativeof the transducer receiving a signal or signal reflection. Thetransducer system and transceiver system interoperate to generate anaggregate sensor view of the roadway intersection. The aggregate sensorview includes a plurality of transducer views of the two or moreapproaches to the roadway intersection. In some embodiments, the trafficsensor is configured to have an aggregate sensor view of approximately270 degrees. In other embodiments, the traffic sensor is configured tohave an aggregate view of approximately 90 degrees. In these otherembodiments, multiple collocated sensors can be used together to providelarger aggregate views.

These and other objects and features of the present invention willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of the invention as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent invention, a more particular description of the invention willbe rendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 illustrates one embodiment of an intersection traffic sensor;

FIG. 2 depicts the example intersection vehicle traffic sensor of FIG. 1in an intersection of roadways and depicts a further aggregate sensorview.

FIG. 3 depicts an example architecture for a switched antennaintersection traffic sensor.

FIG. 4 depicts an example architecture for an electronically steeredantenna intersection traffic sensor.

FIG. 5 depicts an example architecture for a mechanically steeredintersection traffic sensor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The principles of the present invention provide for detecting targets inroadway intersections. A traffic sensor includes a transducer system anda transceiver system.

The transducer system creates a plurality of transducer views of theroadway intersection. Each transducer view can detect targets located ina portion of the roadway intersection. The transducer system includes atransducer configured to transmit signals towards a portion of two ormore approaches to the roadway intersection and configured to receivesignals and signal reflections within the portions of the two or moreapproaches to the roadway intersection.

The transceiver system is configured to generate digital data indicativeof the transducer receiving a signal or signal reflection. Thetransducer system and transceiver system interoperate to generate anaggregate sensor view of the roadway intersection. The aggregate sensorview includes a plurality of transducer views of the two or moreapproaches to the roadway intersection. In some embodiments, the trafficsensor is configured to have an aggregate sensor view of approximately270 degrees. In other embodiments, the traffic sensor is configured tohave an aggregate view of approximately 90 degrees. In these otherembodiments, multiple collocated sensors can be used together to providelarger aggregate views.

In this specification and in the following claims the word “transducer”means a device for converting signals that propagate through the air(e.g., radar signals, electromagnetic signals, acoustic signals, lasersignals, infrared signals, etc.) into electronic signals in a trafficsensor, the word “transducer” can also mean a device for convertingelectronic signals in a traffic sensor into signals that propagatethrough the air. For example, a microwave antenna is a transducer.

In this specification and in the following claims, the term“intersection of roadways” is defined as the intersection of two or moreroadways for automobile and/or truck traffic including the approaches tothe intersection. In this specification and in the following claims, theterm “roadway intersection” is defined to include an intersection ofroadways and also to include an intersection of roadways with one ormore thoroughfares for other traffic, including the approaches to theintersection. Thoroughfares for other traffic may include pedestrianpaths and railways.

FIG. 1 is an example intersection traffic sensor 20. Generally,intersection traffic sensor 20 can be used to detect objects (e.g.,vehicles, pedestrians, etc.) at a roadway intersection. As depicted,traffic sensor 20 includes transducer system 10, transceiver 12,processor 14, and storage 32.

Transceiver 12 is configured to generate signals (e.g., signal 2) andreceive back corresponding signal reflections (e.g., signal reflection3) that result from generated signals reflecting off of an object, suchas, for example, a vehicle. Transceiver 12 is also configured to receivesignals (including any of previously described types of signals) fromother sensors (e.g., signal 4). A generated transmit signal can includea Frequency Modulated Continuous Wave (“FMCW”) radar signal that isgenerated via direct digital synthesis and frequency multiplication. Agenerated transmit signal can also include one or more of a microwavetransmit signal, an acoustic transmit signal, a laser transmit signal, anon-coherent light signal, and an infrared signal.

Processor 14 processes signals and signal reflections received bytransceiver 12 (collectively referred to as sensor data, such as, forexample, sensor data 29) to convert signals and signal reflections intomeaningful digital data (e.g., digital data 6).

Processor 14 can be a digital signal processor configured to convertsignals and signal reflections into digital data and deliver digitaldata to external components, such as, for example, communication link 33(e.g., to a display device or another computer system), storage 37(e.g., a magnetic disk, RAM, etc.), and contact closure 39.

Digital data 6 can include, for example, a sensor configuration,presence indications, vehicle detections, and traffic statistics.Traffic statistics can include: vehicle counts per lane; vehicle countsper direction; vehicle counts per approach; turning counts; averagespeeds per lane, direction, or approach; 85th percentile speeds perlane, direction, or approach; occupancy per lane, direction, orapproach; etc.

Processor 14 can also be configured to control transceiver 12. Forexample, processor 14 can send signal activation command 5 totransceiver 12 when transceiver 12 is to generate a signal.

Transducer system 10 is configured to create areas (hereinafter referredto as “transducer views”) over which a transmit signal is propagatedand/or from which a signal and/or signal reflection is received. In someembodiments, transducer system 10 creates multiple transducer views byswitching between multiple fixed beam antennas, each one steered to adifferent angle. In alternate embodiments, an electronically steerableantenna implemented using phase shifters is used to electronically steerthe antenna beam to different angles thus achieving the differenttransducer views. In still other alternate embodiments, multipletransducer views are created using a single antenna that is connected tothe transceiver 12 via a rotary joint. The antenna is rotated around anaxis so that a different transducer view is available at each instant intime.

These several transducer views form an aggregate sensor view whencombined. Aggregate sensor view means a view as observed by a sensorcomposed of a plurality of transducer views. As depicted in FIG. 1,transducer system 10 creates an aggregate sensor view includingtransducer views 28A-28G. A power level defining the edge of atransducer view can be configured based on the sensitivity oftransceiver 12 and detection algorithms running on processor 14.

FIG. 2 depicts the intersection traffic sensor 20 of FIG. 1 in anintersection of roadways 41. Sensor 20 utilizes multiple transducerviews 24A-24BB which, in combination, form the aggregate sensor view 24.For simplicity, the extent of the aggregate sensor view 24 is depictedas a rectangular. However, the extent of the aggregate sensor view 24 isactually defined by the limits of sensor 20's capabilities and is notnecessarily rectangular.

Transducer system 10 (of FIG. 1) can be configured to switch (e.g.,radar) signal transmission between transducer views 24A-24BB on(transmitting and receiving a signal) and off (not transmitting norreceiving a signal) in sequence. Transceiver 12 (of FIG. 1) can receivea reflected signal (e.g., a radar return) from a range in each of thetransducer views 24A-24BB. The range is the distance between sensor 20and the targets 26A and 26B. By using each of the transducer views24A-24BB, sensor 20 can receive a radar return from multiple azimuthangles, which are measured in the horizontal plane.

Switched Antenna Architecture

FIG. 3 depicts an example architecture 300 for a switched antennaintersection traffic sensor. As depicted, architecture 300 includestransceiver 12A and transducer system 10A. Generally, transceiver 12A isconfigured to receive signal activations, interoperate with transducersystem 10A, and send sensor data.

For example, transceiver 12A can receive signal activation 5A (e.g.,from a processor). Signal activation 5A can be similar to signalactivation 5 from FIG. 1. Signal activation 5A triggers the RF signalgeneration 60A. In one embodiment, the RF signal generation 60A includesdirect digital synthesis and frequency up-conversion. The resultingsignal is a 6 GHz to 6.0625 GHz FMCW chirp. This signal is then routedto one of sixteen quadruplers (e.g., quadruplers 76A-76P) via a 6 GHzswitch (e.g., switch 71). A control line (e.g., control line 77A)controls the 6 GHz switch (e.g., switch 71). The effect of thequadruplers is to quadruple the frequency of the signal resulting in a24 GHz to 24.25 GHz chirp.

The sixteen quadruplers can be switched on (quadrupling the frequency ofthe input signal) and off (not quadrupling the frequency of the inputsignal and providing isolation of the input signal from the output). Thequadruplers are followed by power amplifiers (e.g., amplifiers 72A-72P).These sixteen amplifiers can also be switched on (amplifying) and off(not amplifying). By switching the quadruplers and the power amplifiersthe isolation on the transmit signals can be improved and powerconsumption is reduced by only powering the devices as needed.

Quadrupler and amplifier biasing (e.g., biasing 73A-73P) is used toswitch the quadruplers and amplifiers on and off. The biasing is createdby quadrupler and amplifier bias generation (e.g., quadrupler andamplifier bias generation 70). The quadrupler and amplifier biasgeneration is controlled by the signal activation (e.g., signalactivation 5A). Thus, the signal activation can dictate which of thequadrupler-amplifier pairs are switched on. The quadrupler-amplifierpair that is connected to the RF signal via the 6 GHz switch will beswitched on. The others will be switched off.

Transmission line couplers (e.g., couplers 75A-75P) are used to splitthe signal from the amplifiers (e.g., amplifiers 72A-72P) so that aportion of the signal is delivered to the LO port of the mixers (e.g.,mixers 74A-74P) and a portion is delivered to the transmit antennas(e.g. antennas 78A-78P) in transducers system 10A.

Embodiments of the present invention can include both directionaltransmit antennas and directional receive antennas. When directionaltransmit antennas are used, a plurality of transmit antennas may benecessary to achieve multiple transducer views. Using a plurality ofdirectional transmit antennas (e.g. antennas 78A-78P) decreases thesidelobe level in the two-way antenna patterns and narrows the main beanin the two-way antenna patterns. For example, a directional antenna canhave a mainlobe steered to a specific direction and will have sidelobesin other directions. In some antennas, these sidelobes will receive ortransmit power at an approximate level of −20 dB from the mainlobe. Whentwo identical directional antennas are used as a transmit and receivepair, then the combined sidelobe approximate level is −40 dB. This sameapproximate −40 dB sidelobe level can be achieved if one antenna is usedto both receive and transmit. Furthermore, the same effect that causesthe reduced sidelobe level in the two-way antenna pattern also causes anarrowing of the mainlobe. Thus, when multiple directional transmitantennas are used, the beamwidth of the mainlobe is narrower than if asingle broad transmit antenna is used.

The signal from the receive antennas (e.g., antennas 78AA-78PP) intransducer system 10A is amplified by a low noise amplifier (e.g.,amplifiers 79A-79P). The amplified signal is delivered to the RF port ofthe mixers (e.g., mixers 74A-74P). The intermediate frequency (IF)signal, which in the case of FMCW demodulation is a baseband signal, isproduced at the IF mixer ports. The IF signals from each of the mixers(e.g., mixers 74A-74P) are fed into a baseband switch (e.g., basebandswitch 80).

The baseband switch control (e.g., switch control 77B) is synchronizedwith the quadrupler and amplifier biases and the 6 GHz switch control(e.g., switch control 77A) so that the appropriate baseband is connectedto baseband amplification and filtering (e.g., baseband amplificationand filtering 62A). After the baseband signal is conditioned by thebaseband amplification and filtering, the signal is considered sensordata (e.g., sensor data 29A). This sensor data is digitized andconverted into useful information by a processor (e.g., processor 14).

In one embodiment, the transmit and receive antennas (e.g., antennas78A-78P and 78AA-78PP) in transducer system 10A are traveling waveseries fed microstrip patch antennas that are terminated by a matchedmicrostrip patch. Traveling wave series fed microstrip patch antennascreate a fan shaped antenna beam. This type of antenna is a printedmicrowave antenna that is manufactured using printed circuit boardtechniques. The antennas can be oriented so that the antenna beam isnarrow in the azimuth (or horizontal) plane and wide in the elevation(or vertical) plane. The steer angle of the beam, which is measured inthe azimuth plane, may be dictated by the phasing between the antennaelements. The spacing of the elements at least in part controls thisphasing. For example, antenna 78A can be designed so that its beam issteered to near boresight (perpendicular). Antenna 78P, however, can bedesigned so that its beam is steered to approximately 42° off ofboresight. In this way sixteen (or some other appropriate number of)antennas can be designed with feed points on opposite sides so that thesixteen (or other appropriate number of) antenna beams cover a 90° area.

One embodiment of the traffic sensor will have an aggregate sensor viewof 270°. To achieve this aggregate sensor view, threetransceiver-transducer system pairs such as the ones depicted in FIG. 3are utilized. Each transceiver-transducer system can be oriented at 90°to the adjacent pair, resulting in an aggregate sensor view of 270°.

In another embodiment, the traffic sensor will have an aggregate sensorview of 90°. In this embodiment, multiple traffic sensors will be usedtogether to provide the needed detections. For example, three sensorsmay be mounted on the same pole and oriented 90° from the adjacentsensor(s). In this orientation the aggregate sensor views of each of thesensors will then cover a 270° area.

The processor or processors that control the threetransceiver-transducer system pairs will create three signal activationsignals (e.g., similar to signal activation 5A) and will receive threesensor data signals (e.g., similar to sensor data 29A).

In other embodiments of the switched antenna architecture the sameantenna is used for transmitting and for receiving. In theseembodiments, a directional coupler or circulator can be used to separatethe transmit signal from the receive signal. Alternately, a two portmixer can be used in which the local oscillator (“LO”) signal and theradio frequency (“RF”) signals are injected into the same mixer port.The intermediate frequency (“IF”) signal, which in the case of FMCWdemodulation is a baseband signal, is produced at the other mixer port.

Electronically Steered Antenna Architecture

FIG. 4 depicts an example architecture 400 for an electronically steeredantenna intersection traffic sensor. As depicted, architecture 400includes transceiver 12B and transducer system 10B. Generally,transceiver 12B is configured to receive signal activations,interoperate with transducer system 10B, and send sensor data.

For example, transceiver 12B can receive signal activation 5B (e.g.,from a processor). Signal activation 5B can be similar to signalactivation 5 from FIG. 1. Signal activation 5B triggers the RF signalgeneration 60B. In one embodiment, the RF signal generation 60B consistsof direct digital synthesis, a frequency up-conversion mixing stage, anda frequency multiplication stage. The resulting signal is a 24 GHz to24.25 GHz FMCW chirp. This signal is amplified (as shown by exampleamplifier 66B). A transmission line matched tee (e.g., tee 65B) is usedto split the signal so that a portion of the signal is delivered to themixer (e.g., mixer 68B) and a portion is delivered to the transducersystem 10B. In this embodiment, the matched port of the matched tee isconnected to the two port mixer (e.g., mixer 68B). In alternateembodiments, the transmit and receive signals are separated using adirectional coupler or a circulator and a standard three port mixer canbe used. In still other embodiments, separate transmit and receiveantennas are used.

Amplification and filtering can be performed on the baseband signal (asshown by the baseband amplification and filtering block 62B) to generatethe sensor data (e.g., sensor data 29B). The sensor data can then bedigitized and converted into useful information by a processor (e.g.,processor 14).

One embodiment of the transducer system 10B includes a corporate fedmicrostrip patch array antenna. The corporate feed (e.g., corporate feed50) is designed on a strip line layer to prevent undesired radiation.The corporate feed serves to divide the power between the radiatingpatches (e.g., microstrip patches 54A-54P) such that an amplitude windowacross the array is created. This amplitude window serves to reduce theantenna sidelobes. The strip line layer corporate feed (e.g., corporatefeed 50) transitions to a coplanar transmission line on the outer layerwith a pad to accommodate a surface mount phase shifter (e.g., phaseshifters 52A-52P).

Surface mounted ferroelectric thin film passive phase shifters (e.g.,mounted using a “flip chip” solder reflow method) can be utilized.Ferroelectric thin film passive phase shifters can be used to alter thephase of the signal that is radiated by each individual radiatingelement (e.g., microstrip patches 54A-54P) or to alter the phase of thesignal that is received by each individual radiating element. A phaseshifter control (e.g., phase shifter control 58) generates DC biasvoltages that are transmitted by DC bias lines (e.g., DC bias lines56A-56P) and control the phase shifters (e.g., phase shifters 52A-52P).This phase shifter control can generate the DC bias necessary for eachphase shifter so that the beam that is generated from the antenna arrayis steered in the necessary direction.

In alternate embodiments, phase shifters based on time delays can beused. For example, inside the phase shifter the signal path can beswitched between various delay line lengths. Each different delay linelength will provide a different time delay and provide a different phaseshift.

A calibration process can be utilized to eliminate phase errorsintroduced by variation between phase shifters and/or variation withtemperature. This calibration process may be performed using anartificial tone that is injected into the antenna or using a brighttarget in the view of the sensor.

The radiating elements (e.g., microstrip patches 54A-54P) of transducersystem 10B are located on the opposite side of the printed circuit boardfrom the phase shifters (e.g., phase shifters 52A-52P). Thus, unwantedradiation from the phase shifters can be mitigated.

An electronically steered antenna such as the one described above can bereasonably steered to approximately ±45°.

A preferred embodiment of the traffic sensor can have an aggregatesensor view of 270°. To achieve this aggregate sensor view, threetransceiver-transducer system pairs such as the ones depicted in FIG. 4can be utilized. Each transceiver-transducer system will be oriented at90° to the adjacent pair. In this way, an aggregate sensor view of 270°can be achieved.

In another embodiment, the traffic sensor will have an aggregate sensorview of 90°. In this embodiment, multiple traffic sensors will be usedtogether to provide the needed detections. For example, three sensorsmay be mounted on the same pole and oriented 90° from the adjacentsensor(s). In this orientation the aggregate sensor views of each of thesensors will then cover a 270° area.

The processor that controls the three transceiver-transducer systempairs will create three signal activation signals (e.g., signalactivation 5B) and will receive three sensor data signals (e.g., sensordata 29B).

Mechanically Steered Antenna Architecture

FIG. 5 depicts an example architecture 500 for a mechanically steeredantenna intersection traffic sensor. As depicted, architecture 500includes transceiver 12C and transducer system 10C. Generally,transceiver 12C is configured to receive signal activations,interoperate with transducer system 10C, and send sensor data

For example, transceiver 12C can receive signal activation 5C (e.g.,from a processor). Signal activation 5C can be similar to signalactivation 5 from FIG. 1. Signal activation 5C triggers the RF signalgeneration 60C. In one embodiment, the RF signal generation 60C consistsof direct digital synthesis, a frequency up-conversion mixing stage, anda frequency multiplication stage. The resulting signal is a 24 GHz to24.25 GHz FMCW chirp. This signal is amplified (as shown by exampleamplifier 66C). A transmission line matched tee (e.g., tee 65C) is usedto split the signal so that a portion of the signal is delivered to themixer (e.g., mixer 68C) and a portion is delivered to the transducersystem (e.g. transducer system 10C). In this embodiment, the matchedport of the matched tee is connected to the two port mixer (e.g., mixer68C).

In alternate embodiments, the transmit and receive signals are separatedusing a directional coupler or a circulator and a standard three portmixer can be used. In still other embodiments, separate transmit andreceive antennas are used.

Amplification and filtering are performed on the baseband signal (asshown by the baseband amplification and filtering block 62C) to generatethe sensor data (e.g., sensor data 29C) that can then be digitized andconverted into useful information by a processor (e.g., processor 14).

Embodiments of the transducer system include a series fed microstrippatch array that is terminated in a matched microstrip patch (e.g.,antenna 94). The array is phased so that the beam of the antenna issteered near boresight. The antenna can be printed onto a circuit board(e.g., circuit board 92) that spins by means of a magnetic bearing motor(e.g., motor 90). A magnetic bearing motor uses a magnetic field tosuspend the motor shaft without physical contact. This type of motor isused in preferred embodiments in order to avoid the use of contactrotary bearings that would wear out and cause failure points. The motoris controlled by a control signal generated by a motor controller (e.g.,motor controller 93). The motor controller responds to the signalactivation signal (e.g., signal 5C).

In alternate embodiments, a reflector or dielectric lens is rotated. Inthese embodiments, a radiating source illuminates the reflector ordielectric lens, which becomes a rotating antenna.

A rotary encoder (e.g., rotary encoder 91) can be included on the motorso that the angle information at each instant in time is available inthe sensor data (e.g. sensor data 29C). In one embodiment, a contactlessrotary joint (e.g., rotary joint 98) is used to provide signalconnectivity between the stationary transceiver 12C and the spinningantenna board 92. A stripline transmission line 96 transmits the RFsignal from rotary joint to the antenna 94. The use of a rotary jointallows for multiple 360° revolutions of the antenna (e.g., antenna 94).

In operation, the motor spins at a constant rate while sensor data iscontinually created. Each time an FMCW chirp is transmitted and receivedthe pointing angle of the antenna is included in the sensor data. Inthis way, a near 360° aggregate sensor view can be created.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A traffic sensor for monitoring an intersection of roadways, thetraffic sensor comprising: a mechanically steered transducer forcreating a plurality of transducer views of a portion of theintersection of roadways, the mechanically steered transducer beingconfigured for at least 360° of rotation; a transceiver systemconfigured to: control steering of the mechanically steered transducer;create a signal that is transmitted through the mechanically steeredtransducer; and receive a signal or signal reflection through themechanically steered transducer; and wherein the mechanically steeredtransducer and the transceiver system interoperate to generate anaggregate sensor view, the aggregate sensor view including a pluralityof transducer views of the two or more approaches to the intersection ofroadways.
 2. The traffic sensor as recited in claim 1, wherein themechanically steered transducer is configured for a plurality of 360°revolutions in the same direction.
 3. The traffic sensor as recited inclaim 1, wherein the mechanically steered transducer comprises a printedmicrowave antenna.
 4. The traffic sensor as recited in claim 1, whereinthe transceiver system includes: an RF signal generator for directdigital synthesis and frequency up-conversion of a signal activationinto an RF signal; a magnetic bearing motor for spinning themechanically steerable transducer; a motor controller for controllingthe magnetic bearing motor, activation of the motor controllerresponsive to the signal activation; and a baseband filter forconditioning a received signal or signal reflection into sensor data. 5.The traffic sensor as recited in claim 1, wherein the magneticcontrolled bearing motor comprises a rotary encoder for providing angleinformation in sensor data.
 6. The traffic sensor as recited in claim 1,wherein the transceiver system includes: a mixer configured to: receivea local oscillator signal and a radio frequency signal as input; andproduce an intermediate frequency representative of sensor data signalas output.
 7. The traffic sensor recited in claim 1, wherein thetransceiver system is further configured to: receive a signal activationfrom a processor; send sensor data to the processor.
 8. The trafficsensor as recited in claim 1, wherein the transceiver system beingconfigured to send sensor data to the processor comprises an act of thetransceiver system being configured to send sensor data that includes anamplified and filtered baseband signal output from a mixer and angleinformation from a rotary encoder.